Fig. 5.

Blocking of integrin α_IIbβ₃ reduces Ca²⁺ responses and PS exposure of spreading platelets. Fura-2-loaded platelets were adhered to coated fibrinogen in the absence (control) or presence of tirofiban (1 μg/mL) for 30 min. Rises in Ca²⁺ in single, adhered platelets in response to thrombin (10 nM) measured by fluorescence ratio imaging. a Traces of Ca²⁺ rises of two representative platelets; also brightfield contrast images after 10 min (bars 10 μm). b Fractions of platelets with elevated Ca²⁺ (>1.2-fold signal) after 10 min. c Fractions of platelets binding FITC-annexin A5 after 10 min. Mean ± SEM (n = 4–6); *p < 0.05 versus control